Modes of Dynamic AMPA Receptor Delivery During Synaptic Plasticity

Abstract

Synaptic plasticity is thought to be the cellular basis of processes like memory and learning. This regulation of synaptic strength is mediated by the concentration of AMPA type glutamate receptor available in the synaptic membrane. While it is thus undisputed that integration of AMPA receptors into the synapse is crucial, it is currently debated how AMPA receptors are trafficked to the synapse and especially where these receptors are integrated into the plasma membrane. On the one hand, AMPA receptors have been shown to diffuse through the plasma membrane from dendritic shafts to dendritic spines where they get trapped by scaffolding proteins positioned at the synapse. On the other hand, a strong case has been made for involvement of active recycling of AMPA receptors by endosomal transport and storage vesicles, delivering the receptors straight into dendritic spines. This review discusses the experimental evidence of these two pathways and offers a model that combines elements of both active and passive transport of AMPA receptors. Understanding the dynamics of AMPA receptor trafficking may ultimately broaden our knowledge on the cellular mechanisms underlying information storage and by synaptic contacts in the central nervous system.